Pressure sensor

Claim 2

In a device for measuring a change in magnitude of a physical phenomenon wherein a change in the phenomenon changes a force applied to a semiconductor piezoresistive element, the improvement wherein said piezoresistive element exhibits a conductance that is a linear function of the applied force over a range of forces, means for stressing said element in proportion to such forces to vary the conductance in that range, the semiconductor piezoresistive element being doped with boron and with gold.

Claim 3

In a device for measuring a change in magnitude of a physical phenomenon wherein a change in the phenomenon changes a force applied to a semiconductor piezoresistive element, the improvement wherein said piezoresistive element is of a single conductive type that exhibits a conductance that Is a linear function of the applied force over a range of forces, means including a resilient member prestressing said piezoresistive element an amount to produce a conductance in that range in the absence of such applied force.

Claim 4

In a device for measuring a change in magnitude of a physical phenomenon wherein a change in the phenomenon changes a force applied to a semiconductor piezoresistive element, the improvement wherein said piezoresistive element is of a single conductive type that exhibits a conductance that Is a linear function of the applied force over a range of forces, means including a resilient member prestressing said piezoresistive element an amount to produce a conductance in that range in the absence of such applied force.

Claim 5

In a pressure sensor, a resilient diaphragm responsive to pressure of a fluid to produce a corresponding actuating force, a semiconductor piezoresistive element that exhibits a conductance that is a linear function of an applied force over a range of forces, means for applying a force proportional to said actuating force to said semiconductor element, and means including a resilient member for prestressing said piezoresistive element to produce a conductance in that range in the absence of an applied force.

Claim 6

In a pressure sensor, a resilient diaphragm responsive to pressure of a fluid to produce a corresponding actuating force, a semiconductor piezoresistive element that exhibits a conductance that is a linear function of an applied force over a range of forces, means for applying a force proportional to said actuating force to said semiconductor element, and means including a resilient member for prestressing said piezoresistive element to produce a conductance in that range in the absence of an applied force.

Claim 7

In a device for measuring a change in magnitude of a physical phenomenon, comprising: a unitary piezoresistive semiconductor element of a conductivity type and having a conductance that is a linear function of an actuating force within one force range but not in another force range; means for resiliently prestressing the semiconductor element to set the semiconductor element in a strain condition within said one force range, and means responsive to the physical phenomenon for applying a corresponding force to the semiconductor element whereby the resultant change in conductance is proportional to the change in magnitude of said phenomenon.

Claim 8

In a device for measuring a change in magnitude of a physical phenomenon, comprising: a unitary piezoresistive semiconductor element of a conductivity type and having a conductance that is a linear function of an actuating force within one force range but not in another force range; means for resiliently prestressing the semiconductor element to set the semiconductor element in a strain condition within said one force range, and means responsive to the physical phenomenon for applying a corresponding force to the semiconductor element whereby the resultant change in conductance is proportional to the change in magnitude of said phenomenon.

Claim 9

In a measuring device as defined in claim 4, circuit means including a constant voltage source and a current-measuring device connected in series with each other and said unitary piezoresistive element for measuring the change in current flowing through said piezoresistive element in response to said applied force, whereby the change in magnitude of said phenomenon is indicated.

Claim 10

In a pressure sensor for measuring changes in pressure comprising: a housing having a flexible diaphragm sealingly mounted on one side thereof; a unitary piezoresistive semiconductor element mounted within the housing, said semiconductor element being of a single conductivity type; a mechanical linkage connecting the diaphragm with said semiconductor element whereby pressure acting on the diaphragm applies a force to said semiconductor to cause said semiconductor element to be strained in a corresponding amount; said semiconductor element having a conductance that is a linear function of applied force within one force range but is not a linear function of force in some other force range, and means for resiliently prestressing the semiconductor element independently of such pressure to establish a strain in the semiconductor element corresponding to a force within said one force range.

Claim 11

In a pressure sensor for measuring changes in pressure comprising: a housing having a flexible diaphragm sealingly mounted on one side thereof; a unitary piezoresistive semiconductor element mounted within the housing, said semiconductor element being of a single conductivity type; a mechanical linkage connecting the diaphragm with said semiconductor element whereby pressure acting on the diaphragm applies a force to said semiconductor to cause said semiconductor element to be strained in a corresponding amount; said semiconductor element having a conductance that is a linear function of applied force within one force range but is not a linear function of force in some other force range, and means for resiliently prestressing the semiconductor element independently of such pressure to establish a strain in the semiconductor element corresponding to a force within said one force range.

Claim 12

A pressure sensor as defined in claim 6 wherein the prestressing means comprises a bias spring mounted to apply a prestressing force to the semiconductor element.

Claim 13

A pressure sensor for measuring changes in pressure comprising: a housing having a flexible diaphragm sealingly mounted on one side thereof; a piezoresistive semiconductor element mounted within the housing, said piezoresistive semiconductor element comprising a single crystal of silicon which is doped with boron and gold; a mechanical linkage connecting the diaphragm with said semiconductor element whereby pressure acting on the diaphragm applies a force to said semiconductor to cause said semiconductor element to be strained in a corresponding amount; said semiconductor element having a conductance that is a linear function of the applied force within one force range but is not a linear function of force in some other force range, and means for prestressing the semiconductor element independently of such pressure to establish a strain in the semiconductor element corresponding to a force within said one force range, said prestressing means comprising a bias spring mounted to apply a prestressing force to the semiconductor element.

Claim 14

A pressure sensor for measuring changes in pressure comprising: a housing having a flexible diaphragm sealingly mounted on one side thereof; a piezoresistive semiconductor element mounted within the housing, said piezoresistive semiconductor element comprising a single crystal of silicon which is doped with boron and gold; a mechanical linkage connecting the diaphragm with said semiconductor element whereby pressure acting on the diaphragm applies a force to said semiconductor to cause said semiconductor element to be strained in a corresponding amount; said semiconductor element having a conductance that is a linear function of the applied force within one force range but is not a linear function of force in some other force range, and means for prestressing the semiconductor element independently of such pressure to establish a strain in the semiconductor element corresponding to a force within said one force range, said prestressing means comprising a bias spring mounted to apply a prestressing force to the semiconductor element.

Claim 15

In a device for measuring a change in magnitude of a physical phenomenon, means responsive to a change in said phenomenon to produce a corresponding actuating force, a semiconductor piezoresistive element that exhibits a conductance that is a linear function of an applied force over a range of forces, and means for applying a force proportional to said actuating force to said semiconductor element, said piezoresistive element having a gauge factor that has a temperature coefficient of one sign and a conductance that has a temperature coefficient of the opposite sign, temperature variations of the gauge factor and temperature variations of conductance opposing each other, to maintain the ratio of conductance to applied force substantially independent of changes in temperature and applied force over a substantial part of the range of linearity of conductance.

Claim 16

In a device for measuring a change in magnitude of a physical phenomenon, means responsive to a change in said phenomenon to produce a corresponding actuating force, a semiconductor piezoresistive element that exhibits a conductance that is a linear function of an applied force over a range of forces, and means for applying a force proportional to said actuating force to said semiconductor element, said piezoresistive element having a gauge factor that has a temperature coefficient of one sign and a conductance that has a temperature coefficient of the opposite sign, temperature variations of the gauge factor and temperature variations of conductance opposing each other, to maintain the ratio of conductance to applied force substantially independent of changes in temperature and applied force over a substantial part of the range of linearity of conductance.

Claim 17

A measuring device as defined in claim 9 wherein said temperature variations of gauge factor and conductance produce nearly equal and opposite effects at a point of operation in the upper third of the range of applied force.

Claim 18

In a device for measuring a change in magnitude of a physical phenomenon, means responsive to a change in said phenomenon to produce a corresponding actuating force, a semiconductor piezoresistive element doped with boron and with gold that exhibits a conductance that is a linear function of an applied force over a range of forces, and means for applying a force proportional to said actuating force to said semiconductor element.

Claim 19

In a device for measuring a change in magnitude of a physical phenomenon, means responsive to a change in said phenomenon to produce a corresponding actuating force, a semiconductor piezoresistive element doped with boron and with gold that exhibits a conductance that is a linear function of an applied force over a range of forces, and means for applying a force proportional to said actuating force to said semiconductor element.